Library Mirror

Being you, reader, a wise person you are going to keep a copy of your entire music library in some external storage device.
Here is a simple example on how to keep your external mirror synchronised with your music library:

-r : recursively sync the subfolders;-u : skip files that are newer on the destination folder (update);-v : increase verbosity (print the files that are copied to the destination);–progress : show a progress bar;–size-only : skip files with same size.

This way, a new music file that you added in SOURCE is copied in DEST if not present, or if newer and of a differentsize of the corresponding file (song..) in DEST.
For a two-way synchronisation, just repeat the rsync instruction reversing the order of “$SOURCE” and “$DEST”.

[!!!]End up SOURCE and DEST paths with atrailing slashto copy the directory contents (whereas not having the slash would copy that directory).
[i] Rsync is installed on Ubuntu systems by default [https://help.ubuntu.com/community/rsync].